⚠️ Amphotericin B binds to fungal ergosterol but also interacts with human cholesterol → explaining its major toxicities, especially nephrotoxicity. 💊 Liposomal amphotericin B (Ambisome® or equivalent generic) is the preferred formulation in the UK: far less nephrotoxic and better tolerated than conventional amphotericin B deoxycholate. 👨‍⚕️ Use only under specialist guidance, with strict dosing and monitoring protocols.

📖 About

Polyene antifungal antibiotic produced by Streptomyces nodosus.
Reserved for progressive, potentially life-threatening systemic fungal infections.
Administration and monitoring require senior specialist involvement (Infectious Diseases, Haematology, or ICU).

⚙️ Mode of Action

Binds preferentially to ergosterol in fungal cell membranes.
Forms transmembrane pores → leakage of intracellular K⁺ and Mg²⁺ → cell death.
Partial affinity for mammalian cholesterol explains renal tubular and infusion toxicities.

🩺 Indications

Severe or disseminated candidiasis (including candidaemia).
Cryptococcal meningitis (often combined with flucytosine).
Invasive aspergillosis and other mould infections (e.g. mucormycosis, fusariosis).
Visceral leishmaniasis (specialist tropical use).
Empirical antifungal therapy in high-risk neutropenic fever (specialist setting).

⚠️ Adverse Effects

Infusion-related reactions: fever, rigors, hypotension, nausea — slow infusion and pre-medication reduce risk.
Nephrotoxicity: tubular injury → ↑creatinine, ↓GFR (less with liposomal formulations).
Electrolyte loss: hypokalaemia, hypomagnesaemia, hyponatraemia → risk of arrhythmia.
Haematological: normocytic anaemia (suppression of erythropoietin).
Occasional hepatotoxicity or allergic reactions.

🔄 Drug Interactions

↑ Nephrotoxicity with ciclosporin, tacrolimus, aminoglycosides, or NSAIDs.
Hypokalaemia increases risk of digoxin toxicity and potentiates QT prolongation.
Concomitant diuretics or corticosteroids worsen electrolyte loss.

💉 Dose (Refer to BNF / Product Datasheet)

Formulation / Context	Recommended Dosing Information
💊 Liposomal Amphotericin B (Ambisome® / Generic)	• 3–5 mg/kg/day IV infusion over ≥2 hours. • Use only 5% dextrose for dilution (incompatible with saline). • No test dose required (unlike conventional amphotericin). • Adjust per infection type and response.
💊 Conventional Amphotericin B Deoxycholate (rarely used in UK)	• 0.25–1 mg/kg/day IV in 5% dextrose. • Test dose: 1 mg in 20 mL 5% dextrose over 20–30 min. • ⚠️ Fatal overdose if >1.5 mg/kg/day.
💊 Amphotericin B Lipid Complex (Abelcet®)	• 5 mg/kg/day IV. • Withdrawn from UK market in 2023; retained in some EU/US centres.

🧪 Monitoring

Renal function: U&Es and creatinine at baseline, then ≥twice weekly (daily if unwell).
Electrolytes: K⁺, Mg²⁺, Na⁺ — replace promptly if low.
LFTs and FBC: monitor for hepatotoxicity and anaemia.
Observe during infusion for rigors, anaphylaxis, or arrhythmia.
Ensure pre-hydration with normal saline before and during therapy.

📚 References

BNF: Amphotericin B
UKHSA / Public Health England: Invasive Fungal Infection Guidelines
MHRA Product Information: Ambisome® (liposomal amphotericin B)

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Amphotericin B 💊